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  • Using entity framework to detect changes in related table and action appropriate inserts and deletes

    - by Kohan
    Lets say i have a Person table, a Role table with a trel table PersonRoles linking them as many to many. I create a new person and assign them to 2 roles (role 1, role 3). I then want to edit this person; so i retrieve their data and bind their roles to a checkboxes. I change the values (Deselect role 1 and select role 2 instead) I then post this data back through a viewmodel. Can i then get Entity Framework to update these roles for me, as in delete the entry in PersonRoles to role 1 and then add a new entry as role 2? Or do i have to do the logic for this myself? Cheers, Kohan

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  • Given a Member Access lambda expression, convert it to a specific string representation with full ac

    - by Nathan
    Given an Expression<Func<T, object>> (e.g. x = x.Prop1.SubProp), I want to create a string "Prop1.SubProp" for as deep as necessary. In the case of a single access (e.g. x = x.Prop1), I can easily do this with: MemberExpression body = (expression.Body.NodeType == ExpressionType.Convert) ? (MemberExpression)((UnaryExpression)expression.Body).Operand : (MemberExpression)expression.Body; return body.Member.Name; However, if there is deeper nesting, e.g. x = x.Prop1.SubProp1, this only gets the most deeply nested name, e.g. "SubProp1" instead of "Prop1.SubProp1" Is there anyway to access the full property path of a lambda expression?

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  • How to write sum calculation based on ria service?

    - by KentZhou
    When using ria service for SL app, I can issue following async call to get a group of entity list. LoadOperation<Person> ch = this.AMSContext.Load(this.AMSContext.GetPersonQuery().Where(a => a.PersonID == this.performer.PersonID)); But I want to get some calculation, for example, sum(Commission), sum(Salary), the result is not entity, just a scalar value. How can I do this?

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  • Testing a (big) collection retrieved from a db

    - by Bas
    I'm currently doing integration testing on a live database and I have the following sql statement: var date = DateTime.Parse("01-01-2010 20:30:00"); var result = datacontext.Repository<IObject>().Where(r => r.DateTime > date).First(); Assert.IsFalse(result.Finished); I need to test if the results retrieved from the statement, where the given date is less then the date of the object, have Finished set to False. I do not know how many results I get back and currently I'm getting the first object of the list and check if that object has Finished set to false. I know testing only the first item of the list is not valid testing, as a solution for that I could iterate through the list and check all items on Finished, but putting logic in a Test is kinda going against the concept of writing 'good' tests. So my question is: Does anyone have a good solution of how to properly test the results of this list?

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  • DefaultIfEmpty doesn't work

    - by Freshblood
    Why is array still null after queried by DefaultIfEmpty ? class Program { static void Main(string[] args) { Program[] array = new Program[5]; Program[] query = array.DefaultIfEmpty(new Program()).ToArray(); foreach (var item in query) { Console.WriteLine(item.ToString()); } Console.ReadKey(); } }

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  • validate linqtosql mapping to a model

    - by Coppermill
    I have generated a LinqtoSQL mapping xml file, which I have a valid XSD schema that I check to make sure the XML is correct. Now I want to check that the field type match the Model/Interface for example: checking that the nullable fields are nullable that int are int etc anyone got any ideas if I can do this?

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  • How can I pass in a params of Expression<Func<T, object>> to a method?

    - by Pure.Krome
    Hi folks, I have the following two methods :- public static IQueryable<T> IncludeAssociations<T>(this IQueryable<T> source, params string[] associations) { ... } public static IQueryable<T> IncludeAssociations<T>(this IQueryable<T> source, params Expression<Func<T, object>>[] expressions) { ... } Now, when I try and pass in a params of Expression<Func<T, object>>[], it always calls the first method (the string[]' and of course, that value isNULL`) Eg. Expression<Func<Order, object>> x1 = x => x.User; Expression<Func<Order, object>> x2 = x => x.User.Passport; var foo = _orderRepo .Find() .IncludeAssociations(new {x1, x2} ) .ToList(); Can anyone see what I've done wrong? Why is it thinking my params are a string? Can I force the type, of the 2x variables?

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  • Timeout LinqToSql inserting millions of records

    - by Bas
    I'm inserting approximently 3 million records in a database using this solution. Eventually when the application has been inserting records for a while (my last run lasted around 4 hours), it gives a timeout with the following SqlException: "SqlExcepetion: Timeout expired. The timeoutperiod elapsed prior to completion of the operation or the server is not responding." What's the best way to handle this exception? Is there a way to prevent this from happening or should I catch the exception? Thanks in advance!

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  • ASP.net MVC3 entities, don't know how to count

    - by Spedax
    I have 2 tables, 1 with countries, 1 with states. The states table has a column with Population. I'm using entities and I have created a List of states for the countries public class TblCountries { //Entities for my table country ... public List<tblStates> States { get; set; } } So now I can for example List all the states that belong to a country. Now what I want to do is count the population, so I can show the population that of an entire country. I tried using in my view @foreach (var item in Model.Countries) { @Html.DisplayFor(modelItem => item.States.Count<population>) } But this doesn't work, anyone know how to do this? Thanks in advanced!

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  • Generate dynamic UPDATE command from Expression<Func<T, T>>

    - by Rui Jarimba
    I'm trying to generate an UPDATE command based on Expression trees (for a batch update). Assuming the following UPDATE command: UPDATE Product SET ProductTypeId = 123, ProcessAttempts = ProcessAttempts + 1 For an expression like this: Expression<Func<Product, Product>> updateExpression = entity => new Product() { ProductTypeId = 123, ProcessAttempts = entity.ProcessAttempts + 1 }; How can I generate the SET part of the command? SET ProductTypeId = 123, ProcessAttempts = ProcessAttempts + 1

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  • Accessing non-related entities in LinqToSql entity classes

    - by Chris Johnson
    In LinqToSql, if I want to access a non-related entity in an entity partial class, how do I do this without creating a new DataContext? Here's the scenario: I have the tables Client, IssueType and ClientIssueType. A Client may specify a list of IssueTypes if they do not want to use the default IssueTypes. I have the default IssueTypes in the ClientIssueType table with a ClientId of null. In my Client partial I'd like to try to retrieve all IssueTypes, and if none are found, return all default IssueTypes. The only way I can see of accessing the IssueTypes with a null ClientId is by accessing the table through a new DataContext, which is problematic once I want to start assigning them to Issues. Where am I going wrong?

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  • BindableAttribute, Combobox, Selectedvalue property - WinForms

    - by user63891
    I am deriving from combobox (WinForms) and am providing a new implementation for the Selectedvalue property. It works fine as is, but any change to the selectedvalue property is not updating other controls bound to the same "binding context" to change their values accordingly. I did try adding the BindableAttribute(true) to the property, but still it does nottrigger the change in value to the other linked controls. The control's DataBindings.add(...) is all set up. And other controls are also bound to the same data filed on the same datasource. Any ideas what i am doing wrong.

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  • Refactoring - Speed increase

    - by Michael G
    How can I make this function more efficient. It's currently running at 6 - 45 seconds. I've ran dotTrace profiler on this specific method, and it's total time is anywhere between 6,000ms to 45,000ms. The majority of the time is spent on the "MoveNext" and "GetEnumerator" calls. and example of the times are 71.55% CreateTableFromReportDataColumns - 18, 533* ms - 190 calls -- 55.71% MoveNext - 14,422ms - 10,775 calls What can I do to speed this method up? it gets called a lot, and the seconds add up: private static DataTable CreateTableFromReportDataColumns(Report report) { DataTable table = new DataTable(); HashSet<String> colsToAdd = new HashSet<String> { "DataStream" }; foreach (ReportData reportData in report.ReportDatas) { IEnumerable<string> cols = reportData.ReportDataColumns.Where(c => !String.IsNullOrEmpty(c.Name)).Select(x => x.Name).Distinct(); foreach (var s in cols) { if (!String.IsNullOrEmpty(s)) colsToAdd.Add(s); } } foreach (string col in colsToAdd) { table.Columns.Add(col); } return table; }

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  • Most efficient way to bind a Listbox with SelectionMode=Multiple

    - by Draak
    Hi, I have an ASP.NET webform that has a listbox (lbxRegions) with multi-select option enabled. In my db, I have a table with an xml field that holds a list of regions. I need to populate the listbox with all available regions and then "check off" the list items that match the regions in the db table. The list options also need to be ordered by region name. So, I wrote the following code that works just fine -- no problems. But I was wondering if anyone can think of a better (more succinct, more efficient) way to have done the same thing. Thanks in advance. Dim allRegions = XElement.Load(Server.MapPath(Request.ApplicationPath) & "\Regions.xml").<country>.<regions>.<region> Dim selectedRegions = (From ev In dc.Events Where ev.EventId = 2951).Single.CEURegions.<country>.<regions>.<region> Dim unselectedRegions = allRegions.Except(selectedRegions) Dim selectedItems = From x In selectedRegions Select New ListItem() _ With {.Value = x.@code, .Text = x.Value, .Selected = True} Dim unselectedItems = From x In unselectedRegions Select New ListItem() _ With {.Value = x.@code, .Text = x.Value} Dim allItems = selectedItems.Union(unselectedItems).OrderBy(Function(x) x.Text) lbxRegions.Items.AddRange(allItems.ToArray()) P.S. You can post code in C# if you like.

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  • C# Entity Framework Base Repository

    - by Andy
    I'm trying to create a base repository for use with Entity Framework 4.0 and having some trouble. In this code below, why is it not possible to do this in one line? public IEnumerable<T> GetAll<T>(Expression<Func<T, bool>> filter) { IEnumerable<T> allCustomers = this.GetAll<T>(); IEnumerable<T> result = allCustomers.Where(filter.Compile()); return result; } Won't this result in 2 SQL statements: one without a where clause that retrieves all rows, and one with a where clause that only retrieves the rows that match the predicate? How can this be done with a single SQL statement? I can't get it to compile if I try to cast the filter.Compile() to Func<Customer, bool>. Thanks, Andy

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  • Will my LinqToSql execution be deffered if i filter with IEnumerable<T> instead of IQueryable<T>?

    - by cottsak
    I have been using these common EntityObjectFilters as a "pipes and filters" way to query from a collection a particular item with an ID: public static class EntityObjectFilters { public static T WithID<T>(this IQueryable<T> qry, int ID) where T : IEntityObject { return qry.SingleOrDefault<T>(item => item.ID == ID); } public static T WithID<T>(this IList<T> list, int ID) where T : IEntityObject { return list.SingleOrDefault<T>(item => item.ID == ID); } } ..but i wondered to myself: "can i make this simpler by just creating an extension for all IEnumerable<T> types"? So i came up with this: public static class EntityObjectFilters { public static T WithID<T>(this IEnumerable<T> qry, int ID) where T : IEntityObject { return qry.SingleOrDefault<T>(item => item.ID == ID); } } Now while this appears to yield the same result, i want to know that when applied to IQueryable<T>s will the expression tree be passed to LinqToSql for evaluating as SQL code or will my qry be evaluated in it's entirety first, then iterated with Funcs? I'm suspecting that (as per Richard's answer) the latter will be true which is obviously what i don't want. I want the same result, but the added benefit of the delayed SQL execution for IQueryable<T>s. Can someone confirm for me what will actually happen and provide simple explanation as to how it would work?

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  • Find Elements by Attribute using XDocument

    - by Ignacio
    This query seems to be valid, but I have 0 results. IEnumerable<XElement> users = (from el in XMLDoc.Elements("Users") where (string)el.Attribute("GUID") == userGUID.ToString() select el); My XML is as follows: <?xml version="1.0" encoding="utf-8" standalone="yes"?> <Users> <User GUID="68327fe2-d6f0-403b-a7b6-51860fbf0b2f"> <Key ID="F7000012ECEAD101"> ... </Key> </User> </Users> Do you have any clues to shed some light onto this?

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  • Does a TransactionScope that exists only to select data require a call to Complete()

    - by fordareh
    In order to select data from part of an application that isn't affected by dirty data, I create a TransactionScope that specifies a ReadUncommitted IsolationLevel as per the suggestion from Hanselman here. My question is, do I still need to execute the oTS.Complete() call at the end of the using block even if this transaction scope was not built for the purpose of bridging object dependencies across 2 databases during an Insert, Update, or Delete? Ex: List<string> oStrings = null; using (SomeDataContext oCtxt = new SomeDataContext (sConnStr)) using (TransactionScope oTS = new TransactionScope(TransactionScopeOption.Required, new TransactionOptions { IsolationLevel = System.Transactions.IsolationLevel.ReadUncommitted })) { oStrings = oCtxt.EStrings.ToList(); oTS.Complete(); }

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  • Using reflection to find all linq2sql tables and ensure they match the database

    - by Jake Stevenson
    I'm trying to use reflection to automatically test that all my linq2sql entities match the test database. I thought I'd do this by getting all the classes that inherit from DataContext from my assembly: var contexttypes = Assembly.GetAssembly(typeof (BaseRepository<,>)).GetTypes().Where( t => t.IsSubclassOf(typeof(DataContext))); foreach (var contexttype in contexttypes) { var context = Activator.CreateInstance(contexttype); var tableProperties = type.GetProperties().Where(t=> t.PropertyType.Name == typeof(ITable<>).Name); foreach (var propertyInfo in tableProperties) { var table = (propertyInfo.GetValue(context, null)); } } So far so good, this loops through each ITable< in each datacontext in the project. If I debug the code, "table" is properly instantiated, and if I expand the results view in the debugger I can see actual data. BUT, I can't figure out how to get my code to actually query that table. I'd really like to just be able to do table.FirstOrDefault() to get the top row out of each table and make sure the SQL fetch doesn't fail. But I cant cast that table to be anything I can query. Any suggestions on how I can make this queryable? Just the ability to call .Count() would be enough for me to ensure the entities don't have anything that doesn't match the table columns.

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  • Transform Two Lists into One Different List

    - by Ngu Soon Hui
    I have two lists of double List<double> X List<double> Y And I have a destination object: public class PointD { public double X {get;set;} public double Y {get;set;} } How to transform them into a single list? public static List<PointD> Transform(List<double> X, List<double> Y) { } All the errors checking must be there.

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  • Linq2SQL InfoMessage

    - by Paul Oakham
    Hi, is it possible to access the InfoMessage event handler in a Linq2SQL data context? All of our code uses these messages to display useful information to the end user and since moving to Linq2SQL I cannot figure out how to show these messages. I have checked the connection object of the data context as well as the classes properties with no luck so I'm wondering if it is possible. Thanks in advance.

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  • Which fieldtype is best for storing PRICE values?

    - by BerggreenDK
    Hi there I am wondering whats the best "price field" in MSSQL for a shoplike structure? Looking at this overview: http://www.teratrax.com/sql_guide/data_types/sql_server_data_types.html We have datatypes called money, smallmoney, then we have decimal/numeric and lastly float and real Name, memory/disk-usage and value ranges: Money: 8 bytes (values: -922,337,203,685,477.5808 to +922,337,203,685,477.5807) Smallmoney: 4 bytes (values: -214,748.3648 to +214,748.3647) Decimal: 9 [default, min. 5] bytes (values: -10^38 +1 to 10^38 -1 ) Float: 8 bytes (values: -1.79E+308 to 1.79E+308 ) Real: 4 bytes (values: -3.40E+38 to 3.40E+38 ) My question is: is it really wise to store pricevalues in those types? what about eg. INT? Int: 4 bytes (values: -2,147,483,648 to 2,147,483,647) Lets say a shop uses dollars, they have cents, but I dont see prices being $49.2142342 so the use of a lot of decimals showing cents seems waste of SQL bandwidth. Secondly, most shops wouldn't show any prices near 200.000.000 (not in normal webshops at least... unless someone is trying to sell me a famous tower in Paris) So why not go for an int? An int is fast, its only 4 bytes and you can easily make decimals, by saving values in cents instead of dollars and then divide when you present the values. The other approach would be to use smallmoney which is 4 bytes too, but this will require the math part of the CPU to do the calc, where as Int is integer power... on the downside you will need to divide every single outcome. Are there any "currency" related problems with regionalsettings when using smallmoney/money fields? what will these transfer too in C#/.NET ? Any pros/cons? Go for integer prices or smallmoney or some other? Whats does your experience tell?

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